Whither the Migration of Monarch Butterflies?

Though the number of butterflies in general was radically down this summer, I still saw the occasional monarch. Some appeared frantic. Were they searching in vain for a mate? Other times they'd pause on a flower to take a long drink of nectar. Sometimes I'd just see a flash of orange out of the corner of my eye. No other butterfly can match a monarch's nimble power in flight. The number of sightings, maybe ten in all, wasn't much changed from previous years.

Their longterm prospects, though, are very much in question. Chip Taylor, who has tracked migrations as closely and for as long as anyone, says that monarchs as a species will survive, but their fabulous migration will not. Last year's overwintering numbers on Oyamel fir trees in the mountains of Mexico was the second lowest ever recorded. Resilient as the monarchs are, it's hard to imagine the delicate dynamic of migration surviving the rapidly increasing disruptions of climate change.

Yes, climate has changed in the past. It's said that, before humans started altering the atmosphere, the earth experienced a progression of ice ages every 100,000 years or so. During the last ice age, glaciers extended south almost to what is now NY City. What we have now is change at a speed far beyond the capacity of species to adapt, as our machines pour a massive overdose of carbon dioxide into the atmosphere.

In a blog entry this past August, Taylor explained how extremes of weather can affect the monarchs' capacity to build numbers over the summer and migrate back to Mexico in the fall. Extended heavy rains in early summer can delay egg laying. Warmer temperatures in September and drought in October can impede a fall migration historically aided by cool winds out of the north. What we got this year was hot and dry, with three months of drought and warm weather extending into mid-November. That's a radical departure from anything I've ever witnessed.

Each year towards the end of October, I start looking for news about the migration south to Mexico. The first headline I found confirmed my suspicions: "This fall's monarch butterfly migration through Texas doesn't look promising." Then, finally, a report on-site at the roosting grounds in Mexico. Though a few had been straggling in over the past few weeks, the first largish group of 2000 monarchs wasn't reported until Nov. 21. In past years, monarchs would predictably arrive en masse in the first week of November. Then, after the monarchs had settled into their roosts, the Biosphere Reserve would be opened to tourists mid-month. This year that opening was cancelled, stranding those tourists who had traveled far to witness a unique example of nature's splendor. This is not the only destination being compromised in a world being heated in part by global tourism. There are different ways to show love for nature. Touristic love, which I was a part of in the past, becomes more ironic by the minute.

The radically dry, warm weather we've experience this fall has a lot to do with the increasing instability of the jet stream--high winds out of the west that normally feed us a steady stream of contrasting weather, but can get blocked and diverted north or south, causing weather systems to linger indefinitely. The jet stream is driven by the difference in temperature between the tropics and the arctic. As the arctic heats more quickly than lower latitudes, the temperature gradient is reduced and the jet stream becomes more malleable. 

Consider the extraordinary ambition and brilliance of the monarch butterfly's eastern migration. Huddled overwinter in the mountains of Mexico, its numbers head north in March, then each succeeding generation--usually four total--fans out from Texas to harvest the richness of flowers and milkweed foliage from the whole eastern half of the U.S. and even up into Canada, before somehow knowing how to navigate all of that embodied richness back to their little hideout in Mexico. Over the past million years, the distance flown would have contracted during ice ages, then expanded as the glaciers withdrew. I think of the monarch migration as akin to a rubber band, stretched northward by the supply of nectar and milkweed, then contracting back down to Mexico for the winter.

The vast territorial expansion each summer is surely dependent on numbers. Otherwise, how will the monarchs find each other to mate as they spread out across the continent? Though much different in behavior, the passenger pigeon was also dependent on big numbers. Its demise, more than a century ago, was due to radical habitat change and a wanton harvest and slaughter that Aldo Leopold described as "trigger-itch." Now, our itch is to take photos, and our intention is to preserve. And yet, we watch as the collateral damage of a machine-driven economy accumulates.

A post on the Monarch Watch Blog describes the Symbolic Monarch Migration that school kids in Mexico, the U.S., and Canada take part in. Kids in Mexico send paper monarchs to kids up north in the spring, and vice versa in the fall. Monarchs ignore country boundaries. They are telling anyone who takes time to listen that our interests don't stop at the border, what we do affects people and nature far away. 

One halcyon autumn day when I was a kid, walking across the broad lawns surrounding Yerkes Observatory in Wisconsin, I was astonished by the sight of countless thousands of monarchs flying above me. There was a thrilling collective energy to their flight, not dutifully unidirectional towards the south but instead more like a dance. They seemed to feed off of each other's proximity and energy--an uncanny mix of whimsy, skill, and determination. 

If the great migration were to be lost, monarchs would still persist in pockets further south, but they wouldn't be the same monarchs we've known and loved. Here's a post on how the loss of migration's rigors would change them.

Monarchs Bring Dance, Delight and Larger Meanings to a Backyard

These are the glory days for monarch watching, with the backyard packed with flowers--a veritable feast that we are grateful to provide.

Lovely as it is, the levitated landscape of pinks and yellows, reds and whites, gains a deeper meaning when a monarch arrives to animate the garden with its fanciful, danciful flight. Brilliance of color is matched by brilliance of movement, with glides and hairpin turns, sudden dips or dartings upward, gracing a garden's contours as if its flight were a form of affection. With an uncanny mix of power and whimsy, the monarch looks to know what it's looking for, as it approaches then darts away or doubles back, each minute of its flight a hundred instant decisions. What makes it land on one flower after approaching and rejecting so many others, seemingly the same, is a mystery.

This morning we saw four at once, two of which flew together, then collapsed upon the carport roof, there to mate for a minute while I ran to grab my camera. The one in front looks to be the female, with thicker veins and no little black spot on the wing.

This one here is a male, judging from the less prominent veins,

and those little black spots on either side of its abdomen.

The monarchs were especially drawn to the joe-pye-weed that with the summer's heat and rain have grown to ten feet high, like a mountain range of flowers.

Sometimes, when a monarch flew and flew around the garden, looking, looking, I thought it might be searching not for nectar but for a milkweed plant to lay its eggs on. Our swamp milkweed disappeared some years back, and this year my wife bought this kind, with orange and yellow flowers. Turns out to be tropical milkweed, native to Mexico but not here. It's pretty, easy for nurseries to grow, and rebounds quickly if ravenous monarch larva consume its leaves. It's also said to have some aspects, given the nature of its more tropical growth, that would make our northern native species of milkweed a better option,

like this butterflyweed that is flourishing in a neighbor's garden.

Most of Princeton's milkweed is common milkweed, which is less ornamental, spreads underground, and can be found in fields, along roadsides, and in this case growing at the nearby Princeton High School ecolab wetland. Other species include purple milkweed, a few of which grow at Herrontown Woods, and green milkweed, found years back in the meadows at Tusculum.

The dominant ideology of our day has deprived us of the satisfaction of contributing to something beyond ourselves. I grow more garden and less lawn because I love native plants, but the monarchs connect the garden to something much larger. Each March, starting out from their wintering home on just a few acres in the mountain forests of Mexico, the monarchs stretch themselves across all of eastern North America, ambassadors of beauty, as if to tell us that all our small efforts, spread across the land, are additive in and to nature, that we can contribute to something profound. May the monarch teach us how to find that satisfaction in other aspects of our lives as well.

Monarchs and Glyphosate

It's time for a little Sunday sermon about good and evil, as it pertains to monarchs and herbicide. (I must be channeling my grandfather, who was a chemistry professor during the school year and a minister during the summer.) But before that, a brief, italicized update on the monarch for context:

Monarchs made their traditional appearance in the mountains of Mexico on the Day of the Dead, which is celebrated from Oct. 31 to Nov. 2. By November 2, according to JourneyNorth, the first several thousand arrivals had clustered on evergreen trees in Michoacan, with millions more still channeling south from Texas. Chip Taylor, who has made the monarch his life's work, predicted numbers at least double of last year's record low. 

That's the good news, but the cards are still stacked against the monarch, as long as agricultural practices in the central U.S. and elsewhere are geared towards exterminating the milkweed the monarch depends upon for building its numbers each year as it migrates north. 

Now for a little talk about the good, the bad, and the (far less emotionally gratifying) inbetween. It's human to want to draw a nice, clean line between good and evil. Mixing the two tends to diffuse the delicious, heady, mobilizing energy that drives many political movements. That nice, clean line also saves big-time on the mental energy required to make fine distinctions. But when it comes to chemistry, good and evil are often not inherent in a substance itself, but are more a matter of how much and where.

Take, for instance, the harsh portrayals of glyphosate, which has become famous or infamous as the active ingredient in Monsanto's herbicide, Roundup. It's now broadcast widely to kill weeds in farm fields, and has had a devastating effect on milkweed populations critical for the survival of monarchs. Because of its relatively low toxicity and price, it's also used in very small and targeted amounts by land stewards working to restore forest and grassland habitat. Since the patent expired, glyphosate can be purchased from other companies than Monsanto. Shall we paint with a broad brush, and implicate all who use it as collaborating to poison our world? This assertion I heard made recently by a resident at a town council meeting. She also said, falsely, that glyphosate "is half of Agent Orange, and that's all you need to know."

One doesn't need to make false assertions about glyphosate to question the way it is being used on such a vast scale. As Maraleen Manos-Jones explained as part of a recent, edifying panel discussion at the Princeton Public Library, Monsanto's "Round-up Ready" corn and soybeans now are grown on more than 100 million acres of cropland in the U.S.. Because the crops have been genetically modified to be unaffected by glyphosate, farmers can spray their fields indiscriminately, exterminating all weeds, including the milkweed the monarchs need to survive. Cornfields used to have enough milkweed growing in and around them to support monarchs as they migrated north. No longer.

Meanwhile, even unfarmed areas such as roadsides are being managed in ways detrimental to the monarch. Herbicide use along roadsides and powerline right-of-ways, from my observation, is on the increase, and mowing in August and September wipes out flowers that could nourish adult monarchs, as well as any milkweed the caterpillars may be feeding on.

That, plus the increasing extremes of weather, are the stark reality monarchs now face, and Ms. Manos-Jones is as good as any at sounding the alarm. She was the first non-native woman to find the monarchs' overwintering grounds in Mexico in the 1970s, and by her telling has risked her life to defy the Mexican mafia that, along with local peasants in need of wood, has been cutting and fragmenting the dense forest the monarchs use for winter shelter. To drive home the threat, she used an aerial photo of the forest, showing a patchwork of clearcuts right next to a grove of evergreen forest turned orange by clustering monarchs. She's involved in a program to plant tree seedlings in logged areas.

But she also falls prey to a black and white apportionment of good and evil. Glyphosate is portrayed as a poison, pure and simple. That clear line may stir passion and a following. The thought of any herbicide getting into the body prompts a feeling of violation. But by laying blame on the molecule rather than on how it is used, people who use the herbicide responsibly are wrongly vilified. The indiscriminate casting of blame begins to bear resemblance to the indiscriminate use of herbicide.

At the other end of the political spectrum, one argument used to question the existence of climate change is that carbon dioxide is a good molecule, necessary for plant life, and so couldn't possibly be doing any harm. But carbon dioxide is beneficial or harmful depending on how much and where. Even as a diffuse molecule in the atmosphere, its concentration has a big effect on the planet. In enclosed spaces, artificially high concentrations of carbon dioxide can, like carbon monoxide, be lethal.

As appealing and convenient as it might be to brand glyphosate as an unmitigated evil, it's the least toxic among herbicides that land stewards have available. Now, the question often comes up, why must any herbicide ever be used for habitat restoration. Why don't land stewards just dig up the invasive shrubs? I would have asked the same if I had nothing more than a backyard to tend to. 100 acres of land choked with non-native shrubs whose foliage the wildlife refuse to eat is another matter. We could leave it be if we didn't want wildlife to have an edible landscape. We could dig the shrubs out if we had infinite time and energy, and didn't care about mass disturbance of the soil. Or, we could use tiny, targeted amounts of low-toxicity herbicide in much the way a doctor prescribes medicine.

The comparison of herbicide to medicine is useful. Ever since Silent Spring, environmentalists have been devoted to freeing the landscape of the scourge of chemicals. When it comes to our bodies, however, environmental and medical thinking are seemingly at odds. Many of us prefer organically grown food, yet willingly ingest chemicals in the form of medicine. For instance, we don't view antibiotics as poisons, but instead make a clear distinction between their beneficial, small-scale, targeted use as medicine, and the much criticized, indiscriminate use of them in cattle and poultry feed. Interestingly, the vast scale of current glyphosate use has led to a sharp increase in resistance in weeds, much like indiscriminate use of antibiotics has led to resistant pathogens.

The best medicine targets the pathogen in the body without affecting the healthy tissues. This is precisely what land stewards do when they dab a bit of glyphosate on the cut stump of an invasive shrub in the forest. A healthy skepticism about herbicides need not preclude applying the same distinctions drawn by medicine. In a forest that's been thrown out of balance, glyphosate can play the role of an antibiotic that, in small, directed doses is very low-risk, helpful and even critical, but becomes problematic when overused.

The three other panelists exemplified this more nuanced, pragmatic view.

Michael Gochfeld, Rutgers professor and co-author with his wife of "Butterflies of NJ", delved into the data on monarch population swings year to year. Most memorably, he described how profoundly weather affects the annual butterfly counts that often last only one day. Even if the sun just disappears behind a cloud, the butterflies are apt to disappear as well, and not get counted. He encouraged all interested to participate in the butterfly counts through the local chapter of the North American Butterfly Association.

Robert Somes, a biologist with NJ DEP's Nongame and Endangered Species Program, said that concerns about monarchs are bringing attention to the work he and others are already doing to manage public lands for rare or endangered species. They use prescribed burns to promote habitat for the Aragos skipper, and clear invasives with a mix of minimal herbicides and mechanical methods. This work benefits local as well as migratory pollinators.

Flo Rutherfeld, of the New Jersey's World of Wings Museum, was the last to speak, and gave some tips for gardening that caters to butterflies. Have a variety of plants that will provide flowers from as early in the season to as late as possible. Morning Cloaks and Question Marks overwinter as adults, so are out and about in the spring. Monarchs will spot wildflowers more easily if they are clumped. Leaf litter is important for overwintering butterflies and moths. Some species even use decomposing leaves as their "host plant".

Invasive species are also impacting monarchs and other butterflies. Gochfeld said that Hairstreak number may be dropping due to an invasive ant. (An account of how native ants have a symbiotic relationship with the caterpillars of Coral Hairstreaks can be found here. Invasive ants often displace native ones, severing the symbiotic relationships that have evolved among native species, with cascading consequences.) Rutherfeld mentioned a non-native milkweed called dog-strangling vine that is causing problems in the northeast. An Ontario website called InvadingSpecies describes how this invasive plant interferes in multiple ways with monarch reproduction:

"Impacts of Dog-Strangling Vine

• Dog-strangling vine forms dense stands that overwhelm and crowd out native plants and young trees, preventing forest regeneration.
• Colonies form mats of interwoven vines that are difficult to walk through and interfere with forest management and recreational activities.
• Leaves and roots may be toxic to livestock. Deer and other browsing animals also avoid dog-strangling vine, which can increase grazing pressure on more palatable native plants.
• The vine threatens the monarch butterfly, a species at risk in Ontario. The butterflies lay their eggs on the plant, but the larvae are unable to complete their life cycle and do not survive."

Waiting to Hear About Monarchs

For months, I've had a blog post in the draft folder, entitled "Monarch Rebound." That title reflected the encouraging increase in sightings of monarch butterflies in the Princeton area in 2017, and an encouraging report from Mexico on Oct. 30, as monarchs from all over the eastern U.S. began arriving at their overwintering site in the Sierra Madre mountains west of Mexico City. A Nov. 9 report also sounded upbeat, describing fall '17 as "the latest migration on record," though with large numbers of monarchs still lingering up in the northeastern U.S.

Hurricane Harvey's incredible deluge in Texas may have decimated butterfly populations in that region, but was early enough in the fall that it didn't coincide with the monarchs' migration south, which would funnel down through Texas several weeks later.

The number of monarch butterflies overwintering in Mexico is normally counted in December, after the monarchs have arrived and established their overwintering colonies. An excellent description of their overwintering behavior can be found at Monarch Joint Venture. Last year, the announcement of overwintering numbers came in early February. Numbers for the past two years were up from the all-time lows of the three years prior. With the high numbers of monarchs seen in the northeast this past fall, the population trajectory looked promising.

But the lack of an official count this late in February is unsettling. The Washington Post came out with an article in January reporting that the monarch numbers in Mexico are down, explaining that an unusually warm fall delayed migration south. High numbers were reported along the Atlantic coast flyways, but because migration was so delayed, the butterflies may not have made it to Mexico. And a Feb. 2 report on the west coast's population of monarchs, which overwinters along the coast of California, showed a small decline.

A big problem remains the massive agricultural use of glyphosate on "Roundup Ready" corn and soybeans, which has eliminated milkweed from farmland, particularly in the midwest. Herbicides are also used along roadsides, where just one pass can obliterate longstanding populations of native perennial wildflowers, including milkweed.

Frequent mowing to keep roadsides looking manicured also prevents wildflowers from blooming. Some states are realizing that roadside management could be used to assist monarchs. Reduced mowing not only reduces the burning of fossil fuels driving climate change, but also allows wildflowers to bloom, providing nectar to fuel the monarchs' migration south, assuming they're able to dodge cars and trucks at the same time.

Here's an example of common milkweed growing in an unmowed, unsprayed field next to Quaker Road in Princeton.

Farther out Quaker Road is a field that one fall had dozens of monarchs feasting on nectar from bright yellow tickseed sunflowers. An annual, they have mysteriously disappeared from the field in recent years, though goldenrod remains.

We've converted some detention basins from turf to native grasses/wildflowers in town. This and the many efforts by gardeners to plant milkweed and other wildflowers surely help. But even those of us who make an effort have little choice but to feed the radical changes in climate that pose the greatest threat. We are trapped, by politicians who refuse to take the necessary action against climate change that will finally ween the nation of a dependence on fossil fuels. Until then, nature will remain under invisible chemical attack, even by those of us who want so much to see it thrive.

How Are Monarchs Doing in 2024?

Several times a year, the question of "How are the monarchs doing?" rises in my mind. An internet search typically ends up at Chip Taylor's blog on Monarch Watch. There you will find thoughtful commentary and deep analyses, a mixture of good news and bad news, as this extraordinarily resilient species faces ever greater challenges. In 2024, overwintering numbers in Mexico were the second lowest ever recorded, with 2013 having been the lowest. Chip's more recent posts tell of a rebound this summer, as this robust and prolific species has increased its numbers during its migration, following the growth of milkweed north in a tagteam of successional generations, spreading into all corners of the eastern U.S.. 

I've had maybe five sightings of monarch butterflies this summer--a typical number. One appeared frantic, as if it had been searching the great outdoors in vain for a partner. Another was laying eggs on a patch of common milkweed at Mercer Meadows--a beautiful and hopeful sight. Another, pictured, was in my front yard on busy Harrison Street in Princeton, gathering nectar on a swamp milkweed. 

A few days ago, one was nectaring on a patch of narrow-leaved mountain mint near Herrontown Woods. I was treated to a surprising display of butterfly aggression, as several skippers suddenly ganged up to chase the monarch away from the mountain mint. 

Part of that competitive fervor may have to do with the scarcity of pollinator plants. In a 4.5 acre field, there were only two small patches of mountain mint. Since forests don't supply summer nectar, meadows like this are where monarchs and other pollinators are going to find food and each other. Many meadows and roadsides are being taken over by mugwort, Chinese bushclover, and other invasive species with limited utility for pollinators. Add that threat to all the others: habitat loss, climate change, indiscriminate herbicide use in people's yards and along roadsides. This meadow is preserved, but that's really just the first step in realizing the meadow's potential as habitat that can help sustain species like our beloved Danaus plexippus, aka monarch butterfly.

Related posts:

Growing Monarchs

Do Praying Mantises Eat Monarch Butterflies?

Other previous posts about monarchs

Do Praying Mantises Eat Monarch Butterflies?

It seemed like such a feel good moment, crossing the gas pipeline right of way out at Mountain Lakes. There's a lovely walk up from Mountain Lakes House towards Witherspoon Woods that crosses the treeless strip known as the gas pipeline right of way. 

The opening was enlivened by thistles in full bloom, probably native field thistles, if the whitish underside of the leaves is indicative. And adorning the thistles were multiple monarch butterflies, fluttering as they drank from the flowers. 

It had been years since I'd encountered a native thistle, and I hadn't seen a monarch in several weeks, so to see both together in numbers lifted the spirit. But the idyllic scene developed some disturbing undertones upon taking a closer look. 

There, down the stalk of the flower a little ways, something brown. Do you see it? A big praying mantis, of which there were several. I've long wondered if they could be one reason the monarchs are declining in numbers. 

The answer came quickly. A pair of monarch wings weren't moving, and there, sticking its head out, next to the lifeless remains was one of the praying mantises. 

Here's a clearer angle. 

The Intermixing of Good and Bad

My interest in plants began with organic gardening. When growing food is the objective, praise goes to rich soil and natural predators that eat insect pests. Once my interest turned to native diversity, however, my view of what was good began to change. I noticed that poor soil often harbored richly diverse native plant communities. Too many nutrients could be detrimental. And those natural predators that were keeping pests at bay? Well, the praying mantises we most commonly see are not natural, but were instead imported from China. 

Note: A National Geographic article explores how the praying mantis avoids being poisoned by the toxins in monarch butterflies.

All around the thistles was another invasive, Chinese bushclover, also known as sericea lespedeza or Lespedeza cuneata. I know it well from my years in North Carolina, where it was planted by the Dept. of Transportation as a supposedly good thing, to reduce soil erosion on newly carved road embankments. Proponents claimed its seeds would be a boon for wildlife. It has since become a major invasive pest in grasslands, replacing diverse native species with an inedible monoculture. And the seeds? Reportedly they are too small and pass through the guts of wildlife unutilized.

Its white flowers distinguish it from natives like slender bush clover (Lespedeza virginica), which has pink flowers and is rarely encountered. 

Chinese bushclover is a relatively new invasive in Princeton, but I've seen elsewhere what it can do, and it's only a matter of time before it forms monocultures to rival mugwort. There might have been a time when I would have praised it for its tough roots that hold the soil in place. Being a legume, it has the capacity to fix nitrogen from the atmosphere, enriching the soil. But no herbivore has come forward to limit its rampancy. From a plant diversity perspective, it is a disaster. 

The knowledge that all is not well in the world does not negate the delight in beautiful thistle blossoms and a clustering of monarchs. It just heightens the sense of positive and negative intertwined all around us.

Butterflies in and around Mexico City--a Princeton Connection?

Though I had hoped to visit the mountain range several hours west of Mexico City where our Monarch butterflies overwinter, I had to settle for a few sightings of tiger swallowtails in the city, along with this collection of butterflies suspended above Freda Kahlo's bed.

(Her other bed in the next room has a mirror above it, placed there when she was bedridden for a year, which might explain how she got interested in painting self-portraits.)

On the flight home, the United Airlines "Hemispheres" magazine featured an article on the Monarch butterflies. The article documents the struggle to save the mountain habitat for the Monarchs, particularly the efforts of the World Wildlife Fund to help locals develop income from tourism so that they don't need to keep cutting down the forest to make a living.

That effort has been successful, the mountain habitat is now protected and on the mend, but now the Monarchs' incredible annual journey is threatened by industrial farm practices in the U.S., and the human-caused climate change that is very rapidly altering the timing for the long migration, and increasing the likelihood of extreme weather like droughts.

The situation points out how even heroic efforts to restore habitat are vulnerable to being trumped by the rapid changes being wrought globally to our atmosphere and oceans. If hardships during the 2000 mile migration reduce the number of Monarchs that make it back to their overwintering site in the fall, fewer tourists will make the pilgrimage to see them, which will then undermine the sustaining tourist economy in the Bioreserve and prompt the locals to return to cutting trees down for a living.

The Monarch's precarious situation also points out the cumulative impact of multiple stressors. An overwintering habitat reduced by logging over the years from 50 acres down to 3; the loss of hedgerows and the introduction of Roundup Ready corn and soybeans in the midwest that allows farmers to kill all the "weeds" that used to provide food and breeding grounds for the migrating butterflies; the increasing extremes of weather. All of these conspire, and for those (probably not readers of these posts!) who don't care much about butterflies, the same cumulative environmental stresses can play out on human economies as well.

If one's looking for something empowering in this less than sanguine state of affairs, consider this. It may be that, as rural areas become less supportive of the migrating Monarchs, residential communities will become more and more important. Towns have the water infrastructure to sustain landscapes in deep droughts. A plentiful supply of nectar and milkweed plants in urban areas could keep the Monarchs and many other species going. It's mind-expanding to think that our work here in Princeton and in other towns across the nation could have consequence for a small mountain community in Mexico, and for sustaining an ancient miracle. (In the photo, a Monarch caterpillar feeds on swamp milkweed planted at Mountain Lakes Preserve.)

Other related posts can be found by typing the word Monarch into the search box at the top of this page. An example is "Native plants feed the needy next to Mountain Lakes."

Monarch Population: Up in the East, Down in the West

Monarchs seemed more common this past summer, but it's been a long wait for a status report on their numbers where they overwinter in the mountains of Mexico. This past week, Monarch Watch finally posted some data, confirming our impressions here in New Jersey. The population is two and a half times larger than a year ago. That's the good news in Mexico, as the time for them to begin migrating northward in March approaches.

West of the Rockies, however, the population with its traditional roosts in Pacific Grove and elsewhere is in jeopardy.

This monarch's perching on a swamp milkweed plant. You can tell the plant species by its leaves, which are softer and more narrow than the common and purple milkweeds. Though the monarch larvae require monarch foliage for food, the adults feed on a wide range of flowers, including the buttonbush in the first photo.

First Monarch Seen

The raingarden in the front yard yesterday, next to busy Harrison Street, was where I saw my first monarch of the season in Princeton.

I had been concerned that the cool summer, pleasant as it is for us, could reduce the reproduction of the monarchs as they build their population from one generation to the next through the summer. But I see no mention of that as a factor in a detailed update on the monarch's status by Chip Taylor, at http://monarchwatch.org/blog/. The website also provides a means to report sightings of monarchs, and there's an email discussion group one can also sign up for. Taylor is predicting somewhat larger numbers than last year, but a fuller recovery will require restoring milkweed to the landscape, particularly to farmland in the midwest, where it has been decimated by Roundup Ready corn and soybeans.

From a slightly different angle, the monarch's wings look pretty beaten up. Hopefully it hasn't had to work too hard to find other monarchs.

Feel free to enter your sightings in the comment section below.

Monarch Butterflies' Future Up in the Air

I got a lot of comments on this letter to the editor, which appeared a couple weeks ago in two local papers. 

Even if March finally brings relief from winter’s chill, this spring is sending a shiver down my spine. March is when the monarch butterflies take wing from their small forest enclave in the mountains of Mexico. Their numbers have been dwindling. Since the first count in the 1990s, the overwintering population of monarchs, clustered together on dense evergreen trees, has shrunk from a high of 50 acres down to a mere 1.5 acres of the forest this winter. As the monarchs begin their annual flight north, they have the reproductive capacity to rebound, but they face ever tougher odds.

The monarchs’ fate is literally up in the air. There’s the herbicide that again will be sprayed on more than 150 million acres of Monsanto’s “Roundup Ready” corn in the midwest. Back when tillage was used for weed control, farm fields doubled as pretty good habitat for monarchs. Now, the intense spraying of herbicide-tolerant corn and soybeans has largely exterminated the milkweed the monarch caterpillars cannot survive without.

Also airborne are ever greater numbers of carbon dioxide molecules, drivers of the global weirding that buffets wildlife with increasing extremes of drought, heat and cold. And there’s the political hot air that spawned an irrational subsidy of ethanol production, which since 2007 has motivated farmers to plow up prairie and roadsides to grow more corn and thereby reduce monarch habitat even more. Since the ethanol produced barely equals the energy required to grow the crops, any societal benefit is dwarfed by the vast loss of habitat in the country's heartland.

Precious few monarchs visited Princeton last year. MonarchWatch.org details the conditions that could allow them to rebound to some extent. But the worry is that, like the passenger pigeons that disappeared early in the previous century, monarchs may need a critical mass to sustain their miraculous migration. Other than supporting national efforts to restore habitat, and reducing our fossil fuel consumption from gulps down to sips, we can seek to be optimal hosts to whatever monarchs reach our backyards.

If you have some sunlit areas, DR Greenway and the farmers market are sources for native milkweed species. In my role as a local naturalist, I collected seeds of local genotypes of milkweed last year and plan to grow and share as many as I can. In a world so focused on extraction and consumption, it will take years of effort, advocacy and luck just to keep what we’ve always taken for granted, and to warm up again the feeling of spring.

Note: The Nature Conservancy blog offers some background information on the monarchs' migration, here and here, and the NRDC has a letter writing campaign aimed at the EPA.

Visits By Butterflies

One perk for us stay-in-Princeton types in the summer is the fabulous display of native flowers--the tall, lanky sort that are like slo-mo fireworks, growing, growing, then bursting forth with a show of color. My backyard is filled with them, and I make a point of going out there not only to appreciate their extraordinary work, but also to see what sorts of insects they attract. Achieve a certain stillness, forget all the other things left undone, and a whole new world may open up. In its own miniature way, insect life can be as surprising and compelling as a trip to exotic lands.

Butterflies are a good entry point. Mimi, a friend of this blog, sent me an email, excited about having seen a common wood nymph. She didn't have a camera the first time, but it returned and she was able to get a photo with her phone. Thanks, Mimi! She noted that it was hanging out around the black-eyed susans, morning glories and beebalm, and that the host plant is purple top, a common native grass in our fields.

I haven't seen a wood nymph, but have had visits from a common buckeye, maybe because we have bottlebrush buckeyes in the garden. This one's visiting a boneset, a plant that hosts a whole ecosystem of insects and spiders this time of year.

The upswing in monarch numbers has created more opportunities for magical moments. (This one's visiting ironweed.) Their flight is extraordinary to watch. There's the strength, speed and agility they display when chasing each other, and then there's the way they navigate a garden. A couple evenings ago, one came and stayed awhile. The garden surrounds our patch of grass, so to stand on the lawn and watch a monarch weaving in and out and over the flowered landscape, seeming to check out every plant yet rarely landing and then just for a sip, is like standing at the center of a merry go round. There's a whimsical, carnival ride quality to its flight, as it darts, then coasts, then darts again, changing direction on a dime. It flies with extraordinary confidence, yet seems unsure where it wants to go. This may simply be a matter of my not understanding its motivations. Whatever its aims, there's a feeling of blessing when a monarch comes to the garden. It lives up to its name, for long with the whimsy is a regal, ambassadorial quality, as it graces each plant with its presence before moving quickly on to the next.

Maybe this year I will finally learn the different sorts of swallowtails. This one appears to be a male two-tailed swallowtail, visiting a giant cup-plant in our backyard.

From the link, it looks that females have more blue.

Another magical moment this summer came unexpectedly while clearing trails at Herrontown Woods of debris. Deep in the woods, I lifted a stick and up flew what seemed like a large moth, the size of a monarch but white, pale like a luna moth but squarish in overall shape. It flew up into the canopy and disappeared. Its presence was reassuring, a sign that something of nature's depth persists in our altered world.

Monarch Butterfly Populations Down

Last year, monarch butterflies numbers were up in the Princeton area compared to previous years, but those heartening visits in our gardens and along roadsides did not translate into increased numbers at their overwintering grounds in Mexico.

The announcement of an official count was delayed this year for some reason. Numbers for the western population of monarchs, overwintering in pine and eucalyptus groves in southern California, came out a month earlier, in early February, and were down considerably. Finally, early this month, the announcement came that numbers of eastern monarchs have declined again. They've been lower the past two years, after small increases the two years prior, with 2014 having marked an all-time low. Over the past several decades, the overall trend has been down, with overwintering monarchs filling 44 acres of forest in Mexico in 1997, and only 6 acres this year.

So many factors affect the survival of monarchs. Illegal logging, windstorms, and coldsnaps can affect their overwintering success. This past fall's migration was affected by the series of tropical storms and the unusually warm weather that delayed the monarchs' flight south. Increased use of herbicides for farming genetically engineered crops has decimated the milkweed that monarchs need to reproduce. And then there's the looming hammer of climate change, as political and economic forces keep us trapped in dependency on fossil fuels. We see, in car commercials, town streets and new developments an ever expanding arsenal of exhaust pipes and chimneys aimed at the heart of nature.

There's some good news to mention. Gendarmes (armed police) have reportedly greatly reduced illegal logging in the monarchs' overwintering forests this past year. And people are showing an interest in planting and caring for milkweed. The stunning thing, which for the most part settles in the back of our minds, unthinkable but inextricable, is that the future remains optional.

While the world continues on its path of self-destruction, we can still find pleasure and joy in working with nature, and wonder why so much of humanity just "doesn't get it." This year, I'll be helping create a large native wildflower garden near the parking lot at Herrontown Woods. Except for a few spots like Tusculum, Princeton's open space is mostly forested, and so offers few flowers in summer and fall to sustain pollinating insects like the monarch. But the combination of windfall from storms and the clearing of invasive woody plants has created a clearing at Herrontown Woods that we can now plant. The aim is to replicate my backyard native garden in a publicly accessible space and on a larger scale, with signage so that people can become acquainted with Princeton's native flora. Much of my backyard garden is in turn modeled on the native flora to be found along the canal next to Princeton's Carnegie Lake. Anyone interested in helping the Friends of Herrontown Woods with this project can contact me through this website.

There's also a citizens' science initiative at this link, where you can provide data on monarch sites to a national survey.

Monarch and Dragonfly Migration Update

You can track the monarchs' fall migration with weekly updates at this link. It's heartening to hear the numbers are up from last year's record low, but they still have a long way to go to rebuild the population. The migration is not a steady slog from the northern U.S. and Canada to their winter home west of Mexico City, but instead comes in fits and starts. When the winds are from the north, monarchs can travel more than 100 miles/day. When winds come from the south, the monarchs hang low, feed on whatever flowers present themselves, and wait for favorable winds. To a considerable extent, they hitchhike to Mexico on the wind.

Though I saw only a couple monarch caterpillars all summer--this one was on a stray common milkweed growing at our town tree nursery at Smoyer Park--there was a memorable moment in the backyard garden when a monarch flew in its powerful but phantomlike way in a broad circle around me several times. 

DRAGONFLIES

Along with monarch migration updates, the learner.org site also describes the fall migration of dragonflies, which in at least one instance kestrels are known to accompany. The kestrels chow down on the dragonflies as both species head south. In other words, the food kestrels need travels with them, which is more than one can say for airline travel these days, and of course the kestrels are using a sustainable energy source to get around.

Now that I'm not spending time in parks pushing my kids on the swings, I'm missing the annual dragonfly festivals, in which a layer cake food chain spontaneously appears above the playground. Winged insects emerge from an underground nest, disperse above the lawn, get feasted on by dragonflies that in one case attracted swallows wishing to snack on the dragonflies. It's a rare show of nature's abundance--the sort that Rachel Carson describes in Fable for Tomorrow, the three page first chapter of Silent Spring.

A National Geographic post describes the similarities dragonfly migrations have with those of birds.

Monarchs--A Miracle in Need of a Miracle

As monarch butterflies begin their migration south towards a home they've never seen but somehow know how to get to, in the mountains northwest of Mexico City, the annual miracle we've long taken for granted appears threatened. Overwintering numbers were down by 60% last winter from the year before. The total population of eastern monarchs occupied only three acres in Mexico's 130,000 acre mountain preserve. The word from New Hampshire to Michigan is that sightings are way down this year. I've seen only two of these beautiful creatures in my wildflower-packed backyard this summer, and none laid eggs on the many swamp milkweeds. What a contrast with 2007, when we had great numbers of larvae, some of which we grew in a glass bowl and later released.

Though threats of logging in the overwintering forest have now been greatly reduced, the monarchs face the increasing weather extremes associated with climate change, and the increasingly hostile North American landscape. In other words, the struggle to save the monarchs has shifted from a point source problem (their overwintering habitat) to a nonpoint source problem (the quality of habitat across the eastern U.S. and Canada).

Above all, Monarchs need to encounter milkweed as they head north from Mexico into Texas, then fan out across the midwest and east coast, with one generation giving way to the next. Last year, deep drought in Texas and elsewhere desiccated what milkweed they could find, but the even bigger problem is 100 million or more acres of farmland that once hosted some milkweed, but now have been converted to Roundup Ready corn and soybeans. 90% of corn is now grown in this way, eliminating most weeds. Fields are planted right up to fencelines and roadsides, eliminating even the borders that once were havens for milkweed.

If you drive out Quaker Bridge Road in Princeton, you can see milkweed rising up above the other weeds in a fallow field. Compare this with the picture at this link, of a corn field in Iowa. Corn for as far as the eye can see.

The photo here on the left (closeup below) shows patches of common milkweed (Asclepias syriaca), which spreads underground and is the most common around Princeton. Swamp milkweed blooms later, doesn't spread, and has softer leaves which you'd think the larvae would prefer, but not necessarily. Butterflyweed is a particularly beautiful milkweed with a disk of brilliant orange flowers, occasionally seen in drier meadows. There are additional prairie species of milkweed rarely encountered hereabouts.

With America's heartland becoming so hostile to Monarchs, the question increasingly becomes whether the butterflies will be able to make it to New Jersey in sufficient numbers to take advantage of the milkweed growing here. In the past ten years, acreage of overwintering butterflies in Mexico has dropped from 25 down to 3. The Roundup Ready corn was first sold commercially in 1998. Overuse of Roundup for growing these genetically engineered crops has led some weeds like giant ragweed, pigweed (both of these species grow in Princeton), and many others to gain resistance to glyphosate, the active ingredient in Roundup. Presumably, milkweed has yet to develop resistance.

On the way out to Route 1, I stopped recently near the canal on Quaker Bridge Road to look out on a field where once I saw many Monarchs feasting on a sea of yellow tickseed sunflower (Bidens) blooms. Almost no Bidens there this year, for whatever reason.

Further down the road, near the canal bridge, there was some Bidens, but no Monarchs. Neither did I see any Monarchs on the ribbon of yellow blooms along the right of way at the Sourlands Mountains Preserve the week before.

I doubt these fishermen at the DR Canal noticed any change in the air.

Certainly drivers navigating narrow Quaker Bridge Road would not take note of any absence in the fields around them. The state of the monarch is but one of the changes quietly happening in the blur of green off to the side as we race forward.

It would be a relief if their numbers rise again, as they did after a very low year in 2004/05, but the trend is towards more agricultural herbicide and unstable climate, not less.

One question at the back of my mind is whether they depend at all on large numbers, to find each other to mate, and to make the long flight back to Mexico. Might large numbers help their momentum as they migrate, much like we are swept along by the momentum of the crowd on an urban sidewalk?

After a long drought in sightings, the visit from this monarch in my backyard a few days ago, feasting for an hour on aster and ironweed nectar, was a real gift. I wish for the past luxury of taking them for granted, though it's hard to think of them with anything but a sense of wonder. Now, this miracle needs another--a nation that cares enough to change its farming practices and the kind of energy it uses, if not for the Monarch, then for ourselves.

There was one day, as a boy walking home across the expansive lawn of Yerkes Observatory in Wisconsin, when I looked up to see the sky completely filled with Monarchs passing through. Such a sight stays with you forever. Though the memory is mine, it is each year's new generations of Monarchs, migrating 2500 miles to New Jersey, that bring it back.

In New Jersey, monarchs migrating south get channeled through Cape May. Here's a blog with daily updates on numbers.

Below are some articles:

One on NPR radio, another in The New York Times,
and a USAtoday article, which may pester you with an ad on an attached video.

An explanation of how they navigate can be found here.